15 - Two-dimensional materials and hybrid systems for photodetection

Abstract

Photodetector is an electronic component that can convert photons into electrical signals, which is ubiquitous in industry and daily life. Conventional semiconductors, such as silicon and indium gallium arsenide, have encountered limitations in photodetection due to their bandgap coverage, opacity, inflexibility, and incompatibility with photonic structures. In view of the facts, two-dimensional (2D) materials, for example, graphene and transition metal chalcogenides have attracted much attention in emerging photodetectors owing to their unique electronic, optical, and mechanical properties. These 2D materials alone and its hybrid with other materials enabled new photoresponse effects and photodetection covering ultraviolet, visible, infrared, and terahertz ranges. In this chapter, we will first revisit the major photoresponse effects of 2D materials for the fundamental understanding of optical-to-electrical conversion processes in photodetectors. After that, a series of key figure of merits will be illustrated. Particularly, the noise in photodetectors will be carefully examined for fair evaluation of existing and new photodetectors. Then 2D materials in photodetectors will be classified and discussed in terms of photoconductive gain. Finally, this chapter will conclude with some fascinating progress of photodetection in flexible electronics as well as forthcoming bioelectronics based on 2D material photodetectors.